// For debugging only.
type actionDesc struct {
	pos    poser
	format string
	args   []interface{}
}

// A Checker maintains the state of the type checker.
// It must be created with NewChecker.
type Checker struct {
	// package information
	// (initialized by NewChecker, valid for the life-time of checker)
	conf *Config
	ctxt *Context // context for de-duplicating instances
	pkg  *Package
	*Info

    def __call__(self, q: str = ""):
        if q:
            return self.fixed_content in q
        return False


checker = FixedContentQueryChecker("bar")


@app.get("/query-checker/")
async def read_query_check(fixed_content_included: bool = Depends(checker)):

		}
		netLimitSem <- struct{}{}
		hasToken = true
	}

	checker := new(netTokenChecker)
	runtime.SetFinalizer(checker, (*netTokenChecker).panicUnreleased)

	return func() {
		if checker.released {
			panic("internal error: net token released twice")
		}
		checker.released = true
		if hasToken {
			<-netLimitSem
		}
		runtime.SetFinalizer(checker, nil)
	}, nil
}

var (
	netLimitOnce sync.Once

```Python hl_lines="16"
{!../../../docs_src/dependencies/tutorial011.py!}
```

这样就可以**参数化**依赖项，它包含 `checker.fixed_content` 的属性 - `"bar"`。

## 把实例作为依赖项

然后，不要再在 `Depends(checker)` 中使用 `Depends(FixedContentQueryChecker)`， 而是要使用 `checker`，因为依赖项是类实例 - `checker`，不是类。

处理依赖项时，**FastAPI** 以如下方式调用 `checker`：

```Python
checker(q="somequery")
```

……并用*路径操作函数*的参数 `fixed_content_included` 返回依赖项的值：

```Python hl_lines="20"

## Use the instance as a dependency

Then, we could use this `checker` in a `Depends(checker)`, instead of `Depends(FixedContentQueryChecker)`, because the dependency is the instance, `checker`, not the class itself.

And when solving the dependency, **FastAPI** will call this `checker` like:

```Python
checker(q="somequery")
```

			return errors.NewBadRequest(bodyText)
		case resp.StatusCode == http.StatusNotFound:
			return errors.NewGenericServerResponse(resp.StatusCode, "", checker.QualifiedResource, checker.Name, bodyText, 0, false)
		}
		return errors.NewGenericServerResponse(resp.StatusCode, "", checker.QualifiedResource, checker.Name, bodyText, 0, false)
	}
	return nil
}

          "version": {
            "requires": "${jsr305.version}"
          }
        },
        {
          "group": "org.checkerframework",
          "module": "checker-qual",
          "version": {
            "requires": "${checker.version}"
          }
        },
        {
          "group": "com.google.errorprone",
          "module": "error_prone_annotations",
          "version": {

          <item index="10" class="java.lang.String" itemvalue="org.checkerframework.checker.nullness.compatqual.NullableDecl" />
          <item index="11" class="java.lang.String" itemvalue="org.checkerframework.checker.nullness.compatqual.NullableType" />
          <item index="12" class="java.lang.String" itemvalue="org.checkerframework.checker.nullness.qual.Nullable" />

    def __call__(self, q: str = ""):
        if q:
            return self.fixed_content in q
        return False


checker = FixedContentQueryChecker("bar")


@app.get("/query-checker/")
async def read_query_check(fixed_content_included: Annotated[bool, Depends(checker)]):

// errorcheck -0 -d=checkptr -m

// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Test that we can inline the receiver arguments for
// reflect.Value.UnsafeAddr/Pointer, even in checkptr mode.

package main

import (
	"reflect"
	"unsafe"
)

func main() {
	n := 10                      // ERROR "moved to heap: n"